Clinical and bacteriological efficacies of lomefloxacin and ofloxacin were comparatively estimated in the treatment of 104 urologic patients with nonspecific inflammatory diseases and in 36 urologic patients for prophylaxis of inflammatory complications after surgical interventions. The majority of the urinary tract pathogens i.e. Enterobacteriaceae spp. and gramnegative nonfermenting bacteria were highly susceptible to both the fluoroquinolones. The clinical and bacteriological efficacies of lomefloxacin amounted to 94.4 and 80.7 per cent and those of ofloxacin to 92 and 79.2 per cent respectively. The prophylactic use of lomefloxacin and ofloxacin was efficient in 94.7 and 94.1 per cent of the cases respectively. The antibacterial prophylaxis in urologic patients should be applied not only at the period of surgical interventions but also during the early postoperative period.